Methods, Devices, and Systems for Discontinuous Reception for a Shortened Transmission Time Interval and Processing Time

ABSTRACT

A method and apparatus for discontinuous reception for a shortened transmission time interval and processing time includes a device receiving, from a network, an indication to enable a first TTI which is a shorter TTI than a second TTI for which the device can be enabled. The method further includes the device switching from monitoring for data transmission scheduling assignments under the control of a DRX configuration associated with the second transmission time interval to monitoring for the data transmission scheduling assignments based on the first transmission time interval.

RELATED APPLICATION

The present application is related to and claims benefit under 35 U.S.C.§119(e) of the U.S. Provisional Patent Application Ser. No. 62/374,740,filed Aug. 12, 2016, titled “Methods, Devices, and Systems forDiscontinuous Reception for a Shortened Transmission Time Interval andProcessing Time” (attorney docket no. MM02127-US-PSP), which is commonlyowned with this application by Motorola Mobility LLC, and the entirecontent of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communication andmore particularly to methods, devices, and systems for discontinuousreception for a shortened transmission time interval length and/orshortened processing time associated with a given transmission timeinterval length.

BACKGROUND

In Long-Term Evolution (LTE), time-frequency resources can be dividedinto 1 millisecond (ms) subframes, where each 1 ms subframe includes two0.5 ms slots, and each slot (with normal cyclic prefix (CP) durations)includes seven single carrier frequency-division multiplexing (SC-FDMA)symbols in the time domain for uplink (UL) communication and sevenorthogonal frequency-division multiplexing (OFDM) symbols in the timedomain for downlink (DL) communication. In the frequency domain,resources within a slot are divided into physical resource blocks(PRBs), where each resource block spans 12 contiguous subcarriers.

In current LTE systems, resources are usually assigned using a 1 msminimum transmission time interval (TTI) when data is available fortransmission between an eNodeB (eNB) and user equipment (UE). This isreferred to as dynamic scheduling. Within each scheduled TTI for ULcommunication, a UE transmits data over a physical uplink shared channel(PUSCH) in PRB-pairs indicated by an uplink grant to the UE from an eNBthat schedules the data transmission. For DL communication, the eNBtransmits data over a physical downlink shared channel (PDSCH) inPRB-pairs preceded by a DL assignment from the eNB. The DL assignmentinformation is provided to the UE in a control channel, which isgenerally referred to as a physical downlink control channel (PDCCH).

Discontinuous reception (DRX) functionality is used in LTE to allow UEsto conserve power. Without DRX, a UE is always awake and continuouslymonitors all subframes of a PDCCH for DL assignments. With DRX, the UEpowers down a portion of its circuitry during a DRX sleep mode whenthere are no expected data packets to be received. The eNB configuresDRX with a set of DRX parameters shared with the UE. These DRXparameters can be application dependent such that power and resourcesavings are maximized. The eNB then schedules DL assignments duringperiods when the UE is actively monitoring for them.

While DRX operation results in power savings, it comes at the expense oflatency. On average, a UE using DRX receives transmissions later ascompared to when DRX is not used. This delay can be problematic when thetransmissions are associated with a time-sensitive application executingon the UE.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed invention, and explainvarious principles and advantages of those embodiments.

FIG. 1 shows a schematic diagram illustrating an environment thatsupports discontinuous reception for a shortened TTI length and/or ashortened processing time associated with a given TTI length inaccordance with some embodiments.

FIG. 2 shows a logical flow diagram illustrating a method for monitoringfor data transmission scheduling assignments based on a shortened TTI inaccordance with some embodiments.

FIG. 3 shows time sequence diagrams illustrating DRX operation utilizingboth TTIs and shortened TTIs in accordance with some embodiments.

FIG. 4 shows a time sequence diagram illustrating DRX operationutilizing both TTIs and shortened TTIs in accordance with an embodiment.

FIG. 5 shows time sequence diagrams illustrating DRX operation utilizingboth TTIs and shortened TTIs in accordance with some embodiments.

FIG. 6 shows a time sequence diagram illustrating various DRX parametersused to establish a DRX cycle in accordance with prior art.

FIG. 7 shows a time sequence diagram illustrating DRX functionality fora shortened TTI length and/or shortened processing time in accordancewith an embodiment.

FIG. 8 shows a logical flow diagram illustrating DRX functionality for ashortened TTI length and/or shortened processing time in accordance withsome embodiments.

FIG. 9 shows a logical flow diagram illustrating a method fordetermining a timer value based on DRX operation using a shortened TTIin accordance with some embodiments.

FIG. 10 shows a time sequence diagram illustrating various DRXparameters used to establish a DRX cycle in accordance with anembodiment.

FIG. 11 shows time sequence diagrams illustrating DRX functionality fora shortened TTI length and/or shortened processing time in accordancewith an embodiment.

FIG. 12 shows a block diagram illustrating a method for determining aDRX parameter in accordance with some embodiments.

FIG. 13 shows a block diagram illustrating internal hardware componentsof a UE configurable in accordance with some embodiments.

FIG. 14 shows a block diagram illustrating internal hardware componentsof an eNB configurable in accordance with some embodiments.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present disclosure.

The apparatus and method components have been represented, whereappropriate, by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present teachings so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

DETAILED DESCRIPTION

Generally speaking, pursuant to various embodiments described herein,the present disclosure provides methods, devices, and systems for DRXutilizing a shortened TTI (STTI) length and/or shortened processingtime, associated with a given (longer) TTI length, in a mobilecommunication network. The mobile communication network includes atleast one access network, such as an LTE network. At least some UEs arecapable of operating in the access network using multiple TTI lengths,wherein at least one of those lengths is a STTI length relative to alonger TTI length.

For additional embodiments, UEs are capable of operating using ashortened processing time while using a TTI of longer length to receivetransmissions. When operating in a DRX mode configured using DRXparameters associated with the STTI length and/or the shortenedprocessing time associated with the longer TTI length, the UE can moreefficiently monitor for data transmission scheduling assignments whilestill realizing the power savings of operating in the DRX mode.

A data transmission scheduling assignment, or a scheduling assignmentfor a data transmission, is a transmission a UE receives from an eNB ofan access network that provides information and/or allocates resourcesto the UE to enable the UE to receive a data transmission from the eNB.For example, a data transmission scheduling assignment indicates a PRBand demodulation scheme for a DL data transmission intended for the UE.

The words “monitor” and “scan” are used interchangeably and refer to aUE “listening” or “watching” for an incoming wireless transmission. Forexample, the UE listens or watches for an incoming transmission on aPDCCH over a predetermined time period.

In accordance with the teachings herein, a method performed by a deviceincludes the device receiving from a network an indication to enable afirst TTI which is a shorter TTI than a second TTI for which the devicecan be enabled. The method further includes the device switching frommonitoring for data transmission scheduling assignments under thecontrol of a DRX configuration associated with the second transmissiontime interval to monitoring for the data transmission schedulingassignments based on the first transmission time interval.

Also in accordance with the teachings herein is a device having acommunication interface and a processor operatively coupled together toreceive, from a network, an indication to enable a first transmissiontime interval which is a shorter transmission time interval than asecond transmission time interval for which the device can be enabled.The operatively coupled communication interface and processoradditionally switch from monitoring for data transmission schedulingassignments under the control of a DRX configuration associated with thesecond transmission time interval to monitoring for the datatransmission scheduling assignments based on the first transmission timeinterval.

For some embodiments, the first TTI has a shorter length than the secondTTI. In other embodiments, the first TTI has a same length as the secondTTI but is associated with a shorter data transmission processing timethan a data transmission processing time associated with the second TTI.In further embodiments, the first TTI both has a shorter length than thesecond TTI and is associated with a shorter data transmission processingtime than for the second TTI. The term “shorter” when contrasting oneTTI against another longer TTI, for instance, can indicate that theshorter TTI is shorter in time and/or that a data transmission receivedover the course of the shorter TTI is processed more quickly as comparedto a similar data transmission received over the course of the longerTTI. Data transmission processing time is described in detail infra withreference to FIGS. 10 and 11.

In accordance with the teachings herein, a method performed by a deviceincludes the device monitoring for data transmission schedulingassignments during an active time of a DRX cycle, and detecting atransmission during the active time. The method further includes thedevice starting a first timer, in response to the detecting, wherein thefirst timer is set for a first timer value that specifies an amount oftime between detecting the transmission and starting a second timer thatextends the active time by a second timer value. The first timer valueis determined based on one or both of a selected first TTI length frommultiple TTI lengths for which the device can be enabled and/or aselected shorter first processing time over a second processing timeassociated with a TTI length used by the device. For some embodiments,one or both of the first TTI length or the first processing time isselected based on an indication from a network.

Also in accordance with the teachings herein is a device having acommunication interface and a processor operatively coupled together tomonitor for data transmission scheduling assignments during an activetime of a discontinuous reception cycle and detect a transmission duringthe active time. The operatively coupled communication interface andprocessor additionally start a first timer, in response to thedetection, wherein the first timer is set for a first timer value thatspecifies an amount of time between the detection of the transmissionand starting a second timer that extends the active time by a secondtimer value. The operatively coupled communication interface andprocessor determine the first timer value based on one or both of aselected first transmission time interval length from multipletransmission time interval lengths for which the device can be enabledor a selected shorter first processing time over a second processingtime associated with a transmission time interval length used by thedevice.

In described embodiments, the aforementioned devices are referred to asUEs, which send and receive data using a wireless communication network,such as a high-speed mobile communication network using the LTE standardof operation. UEs can include, as later described, smartphones and otherelectronic data devices, like phablets and tablets, having cellularcapability.

A TTI refers to a time interval for which a radio resource is allocatedto a UE. As used herein, a TTI has associated therewith an allocatedtime duration or “length” and a UE and or eNB processing time durationor simply processing time. Accordingly, a first TTI that is “shorter”than a second TTI could mean, for example, that the first TTI has ashorter length than the second TTI or that the first and second TTIshave the same length but the first TTI has a shorter associated UEprocessing time than the second TTI.

For brevity and clarity in describing some presented embodiments, afirst TTI, which is shorter than a second TTI in length, is alsoreferred to herein as an “STTI” for “short TTI.” The second TTI oflonger length is, thereby, referred to as a “LTTI” for “long TTI” whichfor some embodiments conforms with current LTE standards for a TTI. Forexample, an LTTI is 1 ms (i.e., one subframe) in length while an STTI is0.5 ms (i.e., one slot) in length. In another embodiment, the length ofthe STTI is such that it supports the transmission of two OFDM symbols,or approximately 140 microseconds (μs) in length. For other embodimentsthe STTI has any length in terms of time or number of transmittedsymbols subject to the condition that the STTI is of lesser length thanthe LTTI. In a particular embodiment, an LTTI is fourteen symbols inlength and an STTI is two symbols in length.

Enabling or activating a feature, such as STTI, on a device means tobegin using a certain feature or setting and may include changing aconfiguration, if another configuration is currently being used, orsetting a status or flag in the device. Disabling or deactivating afeature on a device means to stop using the feature. Configuring adevice means to make changes within the device based on a set ofparameters stored within the device and/or provided to the device inorder to enable a certain feature or setting.

FIG. 1 illustrates a schematic diagram of an example environment 100within which may be implemented methods and devices for DRX for ashortened TTI length and/or shortened processing time, in accordancewith the present teachings. As illustrated, the environment 100includes: a mobile communication network having an access network 110,which in this case is a radio access network (RAN); a core network 120;a packet data network (PDN) 130; and two mobile devices, namely UEs 126and 128.

The core network 120 includes multiple types of network elements thatare collectively used for the overall control of managing theconnectivity and location of UEs and managing bearers for communicationwithin the mobile communication network. Bearers are logical data pathswithin the mobile communication network with specific quality of service(QoS) properties. The distribution of functions between the multipletypes of network elements of the core network 120 depends on aparticular system architecture, as defined, for instance, by a set ofprotocols implemented in the mobile communication network.

The RAN 110 includes one or more base stations, which are collectivelyused to provide over-the-air connectivity for mobile devices,communicatively linking them to the core network 120. The UEs 126 and128 are representative of a variety of mobile devices including, forexample, cellular telephones, personal digital assistants (PDAs),smartphones, laptop computers, tablets, phablets, or other handheld orportable electronic devices.

The RAN 110 can use any type of radio access technology (RAT) for mobiledevices to access and communicate using the mobile communicationnetwork. The access network 110 can be a cellular access network, havingat least one cellular tower or base station for facilitating theestablishment of wireless links by one or more mobile devices to theaccess network. Any suitable cellular or cellular-based accesstechnology can be used. Such technologies include, but are not limitedto: an analog access technology such as Advanced Mobile Phone System(AMPS); a digital access technology such as Code Division MultipleAccess (CDMA), Time Division Multiple Access (TDMA), Global System forMobile communication (GSM), integrated Digital Enhanced Network (iDEN),General Packet Radio Service (GPRS), Enhanced Data for GSM Evolution(EDGE), etc.; and/or a next generation access technology such asUniversal Mobile Telecommunication System (UMTS), Wideband CDMA (WCDMA),etc.; or variants thereof.

The PDN 130 can be, for instance, an enterprise network, an InternetProtocol (IP) Multimedia Subsystem (IMS), the Internet, etc., which hasat least one server, e.g., server 118. For a particular embodiment, thePDN 130 represents a system of interconnected computer networks that usethe standard Transmission Control Protocol (TCP)/IP suite. One examplecomputer network is a network operated by a media service provider,which includes one or more media servers, e.g., a media server 118. Themedia server 118 stores and shares media or content including, but notlimited to, videos such as YouTube videos or movies, audio such asmusic, picture files, or other static and/or dynamic content, some ofwhich can be HD media.

Additionally, although not shown, environment 100 can further includeother networks coupled to and supported by the core network 120 andaccessible to the UEs 126, 128. Such networks can include, for example,one or more additional PDNs or one or more Wireless Local Area Networks(WLANs). The WLANs have at least one access point for facilitatingwireless links using, for instance, Institute of Electrical andElectronics Engineers (IEEE) 802.11 standards, also referred to in theart as Wi-Fi technology, or using Worldwide Interoperability forMicrowave Access (WiMax) technology.

For particular embodiments described herein with respect to FIGS. 2through 14, the mobile communication network is a 3rd GenerationPartnership Project (3GPP) network, for instance, an LTE network,wherein the network elements and the mobile devices are configured tooperate and communicate in accordance with and consistent with one ormore 3GPP standards or technical specifications (TS), for instance theLTE specifications or the NexGen or 5G specifications. However, thiscommunication environment 100 implementation is meant only to serve asan example and in no way limit the disclosed embodiments, which mightalternatively be implemented using other types of network deploymentsand associated communication protocols. Additionally, although only UEsare referenced in the FIGS. 2 through 14, the teachings can be extendedto other types of mobile devices establishing connections andcommunicating within the environment 100.

For the illustrated 3GPP network embodiment 100, the RAN network 110 isan Evolved UMTS Terrestrial Radio Access Network (E-UTRANs) having atleast one base station, in this case four eNBs, namely eNB 102, eNB 104,eNB 106, and eNB 108. The base stations serve mobile devices, such asthe UEs 126 and 128, by connecting the mobile devices to the corenetwork 120 and establishing access network bearers for the mobiledevices. Alternatively, the RAN 110 is a legacy UTRAN having at leastone eNB. Additionally, although not shown, the RAN 110 can have multiplesegments connected by one or more RAN routers, with each RAN segmentforming a different IP routing domain. Accordingly, all the mobiledevices connected to the same RAN segment are allocated IP addressesfrom the same address space. The core network 120, which serves the RAN110, is a System Architecture Evolution (SAE) core, also referred to inthe art as an Evolved Packet Core (EPC). The EPC subcomponents include aMobility Management Entity (MME) 112, a Serving Gateway (SGW) 114, a PDNGateway (PGW) 116, and other subcomponents not shown, such as a HomeSubscriber Server (HSS), etc.

Accordingly, functionality and message exchanges to facilitate theteachings herein can be implemented with protocols used in 3GPPnetworks. Such protocols can include, but need not be limited to,Non-Access Stratum (NAS) protocols running between the mobile devicesand the core network and Access Stratum (AS) protocols running betweenthe mobile devices and the eNBs of which Radio Resource Control (RRC) isan example AS protocol, etc. Some NAS and AS protocols are defined, forinstance, in 3GPP TS 23.401. However, in other embodiments, proprietaryprotocols can be used alternative to or in addition to standardprotocols in order to carry out the present teachings. The particularprotocols used, either proprietary or standard, can depend at least inpart on the particular network architecture.

FIG. 2 shows a logical flow diagram illustrating a method 200 formonitoring for data transmission scheduling assignments based on ashortened TTI in accordance with some embodiments. The UE 126, forexample, receives 202 an indication to enable a first TTI, or STTI,which is a shorter transmission time interval than a second TTI, orLTTI, for which a device can be enabled. The UE 126 then monitors 204for data transmission scheduling assignments based on the STTI insteadof under the control of a DRX configuration associated with the LTTI.For example, the UE 126 switches 204 from monitoring for datatransmission scheduling assignments under the control of a discontinuousreception configuration associated with the LTTI to monitoring for thedata transmission scheduling assignments based on the STTI. In oneembodiment, the STTI includes a first set of OFDM symbols, and the LTTIincludes a second set of OFDM symbols. In another embodiment, the UE 126monitoring data transmission scheduling assignments includes the UE 126attempting to decode the data transmission scheduling assignments. Themethod 200 is described in greater detail with reference to FIGS. 3through 8.

FIG. 3 illustrates DRX operation on a UE utilizing both LTTI and STTI inaccordance with some embodiments. These and other embodiments aredescribed herein by reference to the UE 126 with the understanding thatsimilar embodiments involve other devices or other combinations ofdevices configured to operate using a wireless network such as thatshown by environment 100. In particular, FIG. 3 shows four timelines300, 320, 340, and 360, each illustrating a different embodiment for DRXoperation.

Timeline 300 shows DRX operation with a 1 ms TTI length only, asindicated at 308, consistent with existing art. A DRX cycle 302 beginswith an on duration 304. During the on duration 304, the UE 126 activelymonitors a PDCCH established with an eNB of the RAN 110, taken to be theeNB 102. The UE 126 monitors for the length of each TTI of a block 312of TTIs which spans the on duration 304. During this time, the UE 126monitors the PDCCH for a data transmission scheduling assignment sent bythe eNB 102. The PDCCH carries DL control information (DCI), which viathe scheduling assignment indicates to the UE 126 when to monitor aPDSCH established with the eNB 102 for a DL data transmission.

The DRX cycle 302 ends with an off duration 306. As used herein, theterm “off duration” represents an opportunity for DRX in that the offduration can be converted into active scanning time based on DRX timers.The remainder of the DRX cycle 302 represents an opportunity for DRXbecause the UE 126 can actively monitor the PDCCH during this intervalif triggered to do so, such as if a DRX inactivity timer is stillrunning at the end of the on duration 304. As shown, the UE 126 is notactively monitoring the PDCCH during the off duration 306. This is tomaintain brevity and simplicity in describing enclosed embodiments.

With blocks 314, 316, and 318 of contiguous TTIs 308, the DRX cycle 302repeats itself. In each case, an on duration, represented by anillustrated TTI block, is followed by an accompanying off duration. Theresulting discontinuous monitoring of the PDCCH by the UE 126 allows theUE 126 to realize reduced power utilization, resulting in extendedbattery life. The eNB 102 is synced in its timing with the UE 126 sothat data transmission scheduling assignments sent by the eNB 102 arereceived by the UE 126 during an on duration. This is achieved, forexample, by sharing configuration parameters for the DRX cycle 302between the UE 126 and the eNB 102.

As specified by the 3GPP; Technical Specification Group Radio AccessNetwork; Evolved Universal Terrestrial Radio Access; Medium AccessControl Protocol Specification; Release 14 (TS 36.321 V14.0.0),different DRX parameters define and control different aspects of a DRXcycle. A DRX Start Offset parameter, for instance, specifies a subframeat which a DRX cycle begins. A DRX Cycle parameter specifies theduration of the DRX cycle in subframes, and a DRY On-Time specifies theduration of the on-time for the DRX cycle in subframes. In accordancewith existing art, a single subframe has the same length as the TTI 308,namely 1 ms.

In some instances, DRX operation includes both short and long DRX cyclesfor a given TTI. As a time since a last transmission was receivedincreases beyond a threshold time, for example, a UE experiences deepersleep in that the off duration for the long DRX cycle is greater thanthe off duration for the short DRX cycle. A Short DRX Cycle parameter,for instance, specifies a number of PDCCH subframes in the short DRXcycle, and a Long DRY Cycle parameter specifies a number of PDCCHsubframes in the long DRX cycle. Additionally, a DRY short Cycle Timerparameter might specify a number of subframes a short DRX cycle repeatsbefore transitioning to a long DRX cycle, assuming no transmissions arereceived.

Timelines 320, 340, and 360 illustrate, in part, innovation of thepresent teachings and are referenced and contrasted against timeline 300in describing embodiments of some presented claims. In the timelines320, 340, and 360, the UE 126 transitions from LTTI to STTI, at times324, 344, and 364, respectively, in monitoring a SPDCCH for datatransmission scheduling assignments. In one group of embodiments, LTTIs331, 351, and 371 are of the same time length as the TTI 308, namely 1ms. In other groups of embodiments, the LTTI is 331, 351, and 371 are oflonger or shorter length than the TTI 308 while being longer in lengththen STTIs 333, 353, and 373, respectively. For illustrated embodiments,LTTIs 331, 351, and 371 are of the same length as the TTI 308. Further,DRX cycles 322, 342, and 362 are of the same length as the DRX cycle302, sharing both the same on 304 and off 306 durations and start time.The LTTI blocks 332, 352, and 372 are shown in time synch with the TTIblock 312 to simplify describing presented embodiments.

For timeline 320, the LTTI 331 is the TTI with which the UE 126 isenabled upon initially connecting to a network. The UE 126, for example,powers on and connects with a wireless communication network, such as anLTE network. The UE 126 then monitors a PDCCH, or an enhanced PDCCH(EPDCCH), for data transmission scheduling assignments using the LTTI331. As shown, the UE 126 begins DRX operation for the LTTI 331 asillustrated by the DRX cycle 322. The span of the LTTI block 332represents the on duration of the DRX cycle 322. As illustrated, theLTTI blocks 332 and 338 are in time alignment with TTI blocks 312 and318, respectively. For one embodiment, the network determines a set ofDRX parameters for the LTTI 331 and communicates the parameters to theUE 126. For example, the eNB 102 sends the DRX configuration parametersunder a DRX config structure under MAC-MainConfig. In anotherembodiment, the UE 126 determines the set of DRX parameters andcommunicates those parameters to the eNB 102.

When the UE 126 launches an application which can benefit fromlow-latency wireless communication, such as a peer-to-peer gamingapplication or a financial trading application, the UE 126 activates 324a low-latency mode by transitioning from the LTTI 331 to the STTI 333.Under the STTI 333, as shown, the UE 126 continuously monitors for datatransmission scheduling assignments. Continuously monitoring means thatthere are no periods of inactivity during which the UE 126 is notscanning a physical downlink control channel, such as a PDCCH, EPDCCH,LPDCCH, or SPDCCH, for data transmission scheduling assignments. This isillustrated for the timeline 320 by the appearance of the contiguousSTTIs 333 for an STTI interval 326 between the STTI 333 activation time324 and an STTI 333 deactivation time 325. Periods of scanninginactivity, such as the off duration for the DRX cycle 322, representtimes for which reception of a data transmission scheduling assignmentby the UE 126 is delayed at least until the next active scanninginterval. By continuously scanning during STTI utilization, latency isfurther reduced as compared to using DRX.

For some embodiments, the UE 126 continuously monitoring for datatransmission scheduling assignments is preceded by the UE 126 disablingDRX functionality. Disabling DRX functionally means, for instance, thatthe UE 126 suspends discontinuous scanning and may include reconfiguringthe UE 126 and/or setting a flag to disable the DRX functionality. Insome instances, DRX functionality is resumed or reinitialized based onan already implemented set of DRX configuration parameters, such as byreconfiguring the UE 126 with the already implemented set of DRXconfiguration parameters or otherwise enabling the already implementedset of DRX configuration parameters. In other instances, DRXfunctionality is resumed or reinitialized based on a new set of DRXconfiguration parameters.

In the timelines 320 and 340, for example, DRX functionality for LTTI isresumed based on an already implemented set of LTTI DRX configurationparameters. This is illustrated by the LTTI blocks 338 and 358 being intime alignment with the TTI block 318. During the STTI 333 interval 326for timeline 320 and STTI 353 interval 346 for timeline 340, a clock ofthe UE 126 continues to track time for implemented DRX parameters whileDRX functionality is suspended. When DRX functionality is resumed withthe deactivation of STTI, on and off durations align with the sameintervals they would have had if the DRX functionality had beencontinued without interruption.

The deactivation 325 of STTI 333 in timeline 320, for example, occursbefore the on duration represented by the TTI block 316 ends. The UE 126therefore transitions to actively scanning with LTTI 331 until the onduration ends. This is followed by an inactive interval 327 before theUE 126 resumes LTTI 331 scanning for the LTTI block 338. Here, theinactive interval 327 represents the off duration of the LTTI 331 DRXcycle.

Deactivation 345 of the STTI 353 in timeline 340 occurs after the onduration represented by the TTI block 316 ends. The UE 126 thereforetransitions to an inactive interval 347 shorter than the off duration ofthe LTTI 351 DRX cycle before resuming active scanning for the LTTIblock 358 representing the next on duration.

For timeline 360, disabling DRX functionality when activating 364 theSTTI 373 includes disabling the DRX configuration associated with theLTTI 371. DRX scanning for the LTTI 371 is then reinitialized based onthe same or a new set of DRX configuration parameters after the STTI 373scanning is deactivated 365. For the embodiment shown, STTI 373 scanningis continuous over an STTI 373 interval 366. Because DRX scanning isreinitialized, LTTI block 378, representing an on duration, is not shownin time alignment with the TTI block 318 or the LTTI blocks 338 or 358.When DRX scanning is reinitialized with the same DRX configurationparameters used previously, inactive interval 367 is of the sameduration as the off interval for DRX cycle 362. When DRX scanning isreinitialized with a different set of DRX configuration parameters, theinactive interval 367 can be of a different duration than the offinterval for DRX cycle 362.

In one embodiment, the UE 126 receives an indication to disable the STTI373 at 365 from the network. The indication, for example, is transmittedby the eNB 102. The UE 126 then monitors for data transmissionscheduling assignments under the control of a DRX configurationassociated with the LTTI 371. For a further embodiment, the UE 126 alsoreceives an indication to again enable LTTI 371 scanning from thenetwork.

In a case for which STTI is configured, for example, via RRC, oractivated, for example, via a medium access control (MAC) controlelement (CE), the already configured DRX cycle may be disabled sinceconfiguring/activating STTI is usually associated with low-latencyoperation and DRX operation generally introduces additional latency.

For some embodiments, different on-durations are used before and afterSTTI being enabled. For example, more active time is provided to reducelatency by increasing an on-duration timer. In another example, the UE126 uses different DRX Short Cycle Timers before and after STTI beingenabled. For instance, a higher value for the DRX Short Cycle Timer canbe used after STTI is enabled.

FIG. 4 shows a time sequence diagram of a UE monitoring for datatransmission scheduling assignments using both LTTI 414 and STTI 424 atdifferent times. Here, scanning under the STTI 424 is no longercontinuous as it was for embodiments described with reference to FIG. 3.Both LTTI 414 and STTI 424 scanning are configured for independent LTTI410 and STTI 420 DRX cycles. As shown on timeline 400, the DRX cycle 410is associated with configuration parameters resulting in an on duration412 and an off duration 413. Whereas, the DRX cycle 420 is associatedwith configuration parameters resulting in an on duration 422 and an offduration 423.

STTI activation occurring at 418 results from the UE 126 receiving anindication from the eNB 102. In another embodiment, the UE 126transitions from LTTI 414 scanning to STTI 424 scanning as a result of aparticular application, which benefits from low-latency wirelesscommunication, launching on the UE 126. In one instance, active LTTI 414scanning transitions directly to STTI 424 scanning. As shown fortimeline 400, STTI 424 activation 418 is followed by an inactiveinterval 403 before active STTI 424 scanning occurs for the on duration422 of the DRX cycle 420. For a particular embodiment, the duration ofthe inactive interval 403 is the same as for the off duration 423 of theDRX cycle 420.

In one embodiment, the STTI 424 is associated with a first DRXconfiguration, and the LTTI 414 is associated with a second DRXconfiguration, wherein the first and second DRX configurations includedifferent DRX parameters. The UE 126 enables the first DRX configurationusing the associated DRX parameters to control monitoring for datatransmission scheduling assignments based on the STTI 424. For anotherembodiment, the UE 126 disables the second DRX configuration beforeenabling the first DRX configuration.

In a further embodiment, the first DRX configuration provides a longeractive time for monitoring for the data transmission schedulingassignments than the second DRX configuration. Active time is a timerelated to DRX operation, during which the MAC entity monitors thescheduling assignment (e.g. PDCCH). The same Active Time can apply toall activated serving cell(s). For example, the DRX parameters for thefirst DRX configuration includes a first on-duration timer value, andthe DRX parameters for the second DRX configuration includes a secondon-duration timer value, so that the longer active time is due at leastin part to the first on-duration timer value being larger than thesecond on-duration timer value. This results in the STTI 424 on duration422 being longer than the LTTI 414 on duration 412. With a longer onduration 422, there is a greater probability that the UE 126 willreceive a data transmission scheduling assignment while activelyscanning without having to wait until the next on duration.

In an additional embodiment, the off duration 423 for STTI 424 scanningis shorter than the off duration for LTTI 414 scanning. This furtherreduces latency as the UE 126 monitors for data transmission schedulingassignments using the STTI 424.

The UE 126 can receive a first set of DRX parameters for the first DRXconfiguration for STTI 424 scanning and a second set of DRX parametersfor the second DRX configuration for LTTI 414 scanning from the networkbefore receiving the indication to enable STTI 424 scanning. The UE 126,accordingly, selects STTI 424 scanning and configures itself using thefirst set of DRX parameters after receiving the indication to enableSTTI 424 scanning, to enable the first DRX configuration.

The UE 126 can also receive a second set of DRX parameters for thesecond DRX configuration for LTTI 414 scanning from the network beforereceiving the indication to enable STTI 424. The UE 126 receives a firstset of DRX parameters for the first DRX configuration for STTI 424scanning from the network at the time of or after receiving theindication to enable the STTI 424 scanning, wherein the first DRXparameters are used to enable the first DRX configuration.

For another embodiment, the UE 126 also monitors for data schedulingassignments corresponding to LTTI in subframes when the UE 126 monitorsfor data scheduling assignments corresponding to STTI. For example, theUE 126 uses both the LTTI 414 and the STTI 424 for monitoring during theon duration 422.

FIG. 5 shows four timelines 50X), 510, 520, 530 collectivelyillustrating the combining of two separate DRX cycles 502, 512 into athird DRX cycle, 522 or 532, which governs the UE 126 monitoring fordata transmission scheduling assignments. STTI 518 of the timeline 510is associated with a first DRX configuration that represents the DRXcycle 512 having an on duration 514 and an off duration 516. LTTI 508 ofthe timeline 500 is associated with a second DRX configuration thatrepresents the DRX cycle 502 having an on duration 504 and an offduration 506. In a particular embodiment, the LTTI 508 is 1 ms inlength. The first and second DRX configurations include different DRXparameters, resulting in the DRX cycles 502 and 512 having different onand off durations. The UE 126 determines a third DRX configuration basedon the first and second DRX configurations. It is the third DRXconfiguration that controls the UE 126 monitoring for data transmissionscheduling assignments based on both the STTI 518 and the LTTI 508.

The UE 126 determines the third DRX configuration by determining a unionof at least one of the DRX parameters of the first and second DRXconfigurations. For one embodiment, determining a union of at least oneof the DRX parameters of the first and second DRX configurationsincludes the UE 126 determining a union of a first active time formonitoring for the data transmission scheduling assignments and a secondactive time for monitoring for the data transmission schedulingassignments, wherein the first active time is provided by the first DRXconfiguration and the second active time is provided by the second DRXconfiguration.

The union of the on durations 504 and 514 results in an on duration 524,one of two on durations in the DRX cycle 522. Because the on duration504 is associated with an expectation of receiving a schedulingassignment using the LTTI 508, and the on duration 514 is associatedwith an expectation of receiving a scheduling assignment using the STTI518, the UE 126 scans for both types of scheduling assignments duringthe on duration 524 by using both the LTTI 508 and the STTI 518, asindicated by dotted lines. Less than halfway into the on duration 524,for example, the eNB 102 sends a data transmission scheduling assignmentto the UE 126. The UE 126 is able to receive and decode the transmissionregardless of whether the eNB 102 sent the transmission using the LTTI508 or the STTI 518.

In a further embodiment, the UE 126 only scans for STTI 518transmissions during an on duration 526, the second of the two ondurations for the DRX cycle 522. This is because the on duration 526results solely from an active on duration of the timeline 510. The DRXcycle 502 makes no contribution to the union during the off duration506. Therefore, there is an expectation that the network will send onlySTTI 518 transmissions, and no LTTI 508 transmissions, to the UE 126during the on duration 526.

The DRX cycle 522 has off durations 525 and 527. Each of the two offdurations 525, 527 represents when off duration 506 for the timeline 500overlaps with the off durations of the timeline 510, when the UE 126 isneither expecting an LTTI 508 nor an STTI 518 transmission from thenetwork.

For another embodiment, determining a union of at least one of the DRXparameters of the first and second DRX configurations includes the UE126 determining a union of a first inactive time for monitoring for thedata transmission scheduling assignments and a second inactive time formonitoring for the data transmission scheduling assignments, wherein thefirst inactive time is provided by the first DRX configuration and thesecond inactive time is provided by the second DRX configuration. Thetimeline 530, which includes an on duration 534 and an off duration 536,illustrates one such embodiment. For the timeline 530, the UE 126enforces both the off durations of the timeline 500 and the offdurations of the timeline 510. The timeline 530 shows an off durationwhen either of the timelines 500 and 510 show an off duration, whichincludes when both of the timelines 500 and 510 show an off duration.

FIG. 6 shows a time sequence diagram illustrating various DRX parametersused to establish a DRX cycle in accordance with prior art. In additionto the parameters associated with the timeline 300 of FIG. 3, a timeline600 of FIG. 6 also illustrates parameters connected to an inactivitytimer interval 624, a hybrid automatic repeat request round trip (HARQRTT) timer interval 626, and a retransmission timer interval 628. Theestablished DRX cycle presented in FIG. 6 is associated with a TTI onesubframe in length corresponding to a 1 ms duration.

A set of DRX configuration parameters controls the expiration of thevarious timers illustrated in FIG. 6. The passage of time over which thetimers run is measured by a clock internal to the UE 126. In someinstances, the clock of the UE 126 is synched, up to a constant shift ortiming advance, with a clock of the network when the UE 126 receivestimekeeping signals from the network.

For a time interval 612, an on-duration timer for DRX cycle 610 startsand runs until its expiration. During this time, the UE 126 activelymonitors for data transmission scheduling assignments. For the remainderof the DRX cycle 610, the UE 126 sleeps and does not actively scan fordata transmission scheduling assignments. This provides power savings atthe expense of latency.

As the on-duration timer again runs over a time interval 622 at thebeginning of DRX cycle 620, the UE 126 receives a data transmissionscheduling assignment from the eNB 102 at time 605. Reception of thedata transmission scheduling assignment initializes the inactivity timerwhich runs over the time interval 624. The UE 126 continues to scan fordata transmission scheduling assignments beyond the expiration of theon-duration timer corresponding to the time interval 622 until theinactivity timer corresponding to the time interval 624 expires.Reception of the data transmission scheduling assignment at time 605causes the UE 126 to actively scan during the DRX cycle 620 longer thanit otherwise would have. The philosophy is that if the network isactively communicating with the UE 126, then the network is more likelyto send another communication in the near future than if the datatransmission scheduling assignment at time 605 had not been received. Ifanother data transmission scheduling assignment is received before theinactivity timer corresponding to the time interval 624 expires, thenthe inactivity timer corresponding to the time interval 624 isreinitialized, again extending the period of active scanning by the UE126.

Reception at 605 of the data transmission scheduling assignment forscheduling a data transmission corresponding to a HARQ process alsostarts the HARQ RTT timer for that HARQ process, which runs over thetime interval 626. The parameter controlling the duration 626 of theHARQ RTT timer specifies the minimum number of subframes, or 1 ms TTIs,before a downlink retransmission of the data transmission scheduled bythe scheduling assignment transmitted at time 605 is expected from thenetwork. After the network sends the data transmission schedulingassignment the UE 126 is shown to receive at time 605, the network waitsto receive an acknowledgement (ACK) that the UE 126 received andsuccessfully decoded the corresponding data transmission.

Sometimes, the UE 126 does not receive a transmission, or if it doesreceive the transmission, it fails to decode it. For a data transmissionthat was not successfully decoded, the network does not get an ACK backfrom the UE 126. This triggers the network to send another datatransmission scheduling assignment after the HARQ RTT timercorresponding to the time interval 626 expires and during the timeinterval 628 when the retransmission timer is running and the UE 126 isactively scanning for the transmission. After the retransmission timerexpires, the UE 126 sleeps until the next DRX cycle when the on-durationtimer again runs over the time duration 632.

The parameter that controls the time duration 626 the HARQ RTT timerruns is chosen to account for a “round-trip” transmission time andprocessing time for the UE 126 to decode a data transmission. Only whenthe network fails to receive an ACK, or it receives a negativeacknowledgement (NACK), does the network resend the data. Therefore, theHARQ RTT parameter takes into account the travel time of the datatransmission to the UE 126, the processing time for the UE 126 to decodethe transmission, and the time for the UE's ACK to reach and beprocessed by the network.

FIG. 7 shows a time sequence diagram illustrating DRX functionality fora shortened TTI length with the UE 126 receiving control informationfrom the network in two parts, also referred to herein as “levels,” attwo discrete times. In particular, FIG. 7 shows a timeline 710 for whichthe UE 126 actively scans for two-level data transmission schedulingassignments using STTI 706. Two contiguous 1 ms subframes 720, 730 areshown, each framed by a bold border and each having a span of sevencontiguous 143 μs STTIs 706. Under ideal conditions, the UE 126 receivesa first-level DCI at 722 during the first STTI of the subframe 720. Thefirst-level DCI includes information the UE 126 uses to decode asecond-level DCI received at 724, during the sixth STTI of the subframe720. Under less than ideal conditions, the UE 126 fails to receive orfails to decode the first-level DCI at 722. The UE 126 discontinuesscanning because it does not have the information from the first-levelDCI to decode the second part of the scheduling assignment.

For an embodiment in accordance with the present teachings, the UE 126monitoring for data transmission scheduling assignments based on theSTTI 706 includes the UE 126 monitoring for the data transmissionscheduling assignments under the control of a DRX configurationassociated with the STTI 706 and specified by a set of DRX parameters.The UE 126 is configured for an active time for performing themonitoring and an inactive time for disabling the monitoring, whereinthe active and inactive times are based on a first parameter of the setof DRX parameters. When the UE 126 detects only one part of a two-partscheduling assignment while monitoring during the active time, itextends the active time by an additional time period to continueperforming the monitoring, wherein the additional time period is basedon a second parameter of the set of DRX parameters.

As shown, for example, the UE 126 fails to receive the first-level DCIat 722 while an inactivity timer is running over a time period 728. TheUE 126 does, however, receive the second part of the schedulingassignment at 724 but is unable to decode it for lack of having receivedthe first part. Had the UE 126 received and decoded the two-partscheduling assignment in its entirety, it would have extended theinactivity timer by an additional time period 738. For the illustratedembodiment, reception of the second-level DCI at 724 alone serves as anindication to the UE 126 that the network is attempting to schedule it.As a consequence, the UE 126 extends the inactivity timer and continuesto actively scan for the network's next scheduling transmissions, forexample, to receive a first- and second-level DCI at 732 and 734,respectively. For the embodiment shown, the inactivity timer is extendedby an additional time period of one subframe in length. In otherembodiments, the additional time period by which the inactivity timer isextended can amount to any number of subframes or individual STTIs.

FIG. 8 shows a flow diagram illustrating a method 800 involving DRXfunctionality for receiving control information in two parts while usinga shortened TTI length. The method 800 begins with the UE 126determining 802 if its DRX mode is configured and enabled. If the DRXmode is not enabled on the UE 126, then the UE 126 monitors 804 anSPDCCH (a PDCCH using STTI) for second-level DCI decoding candidates insubframes where a first level DCI is decoded. If the first-level DCI isdecoded, then the second-level DCI is a candidate for decoding. If thefirst-level DCI is not successfully decoded, then the second-level DCIis not a candidate for decoding because the UE 126 cannot decode thesecond-level DCI without having decoded the first level DCI. With DRXdisabled, the UE 126 scans continuously and receives the next two-levelDCI transmission from the network in a following subframe.

If the UE 126 determines 802 its DRX mode is configured and enabled,then the UE 126 monitors 808 the SPDCCH for second-level decodingcandidates in subframes for which a first-level DCI is monitored,whether the detected first-level DCI is successfully decoded or not. Ifthe first-level DCI is decoded, then the UE 126 monitors for and decodesthe second-level DCI. If the first-level DCI is not decoded, the UE 126still monitors for the second-level DCI as a decoding candidate eventhough the second-level DCI cannot be decoded. In this case, receivingthe second-level DCI triggers an extension of the inactivity timer by anadditional time period when the DRX mode is enabled on the UE 126.

In another embodiment, as indicated by broken lines, the UE 126determines 806 if the eNB 102 has enabled a partial SPDCCH monitoringfeature while the DRX mode is enabled on the UE 126. If the partialSPDCCH monitoring feature is enabled on the UE 126 by the eNB 102, thenthe UE 126 monitors 808 the SPDCCH for second-level decoding candidatesin subframes for which a first-level DCI is decoded or only monitoredand not necessarily decoded as previously described for box 808. If,however, the UE 126 determines 806 partial SPDCCH monitoring is notenabled, then the UE 126 monitors 804 the SPDCCH for second-level DCIdecoding candidates in subframes where a first level DCI is decoded aspreviously described for box 804.

Partial SPDCCH monitoring allows for selective monitoring ofsecond-level DCI decoding candidates when a DRX mode is enabled on theUE 126. In particular, it allows the network to control when to monitorfor second-level DCI decoding candidates given that a first-level DCI ismonitored but not decoded. For some embodiments, the network activatesor deactivates selective monitoring depending upon values for DRXconfiguration parameters. In other embodiments, the network activates ordeactivates selective monitoring on the UE 126 depending upon traffictype as determined by an identifiable category of communicationoccurring between the network and the UE 126. The network, for example,communicates a selective monitoring setting to the UE 126 usingphysical-layer or higher-layer signaling.

FIG. 9 shows a logical flow diagram illustrating a method 900 fordetermining a timer value based on DRX operation using a shortened TTIin accordance with some embodiments. The UE 126, for example, monitors902 for data transmission scheduling assignments during an active timeof a DRX cycle. During the active time, the UE 126 detects 904 atransmission. The UE 126 then starts 906 a first timer set for a firsttimer value that specifies an amount of time between detecting thetransmission and starting a second timer that extends the active time bya second timer value. For some embodiments, the first timer is a HARQRTT timer and the second timer is a retransmission timer. The method 900is described in greater detail with reference to FIGS. 10 through 12.

FIG. 10 shows a time sequence diagram illustrating various DRXparameters used to establish a DRX cycle in accordance with the presentteachings. The sequence diagram includes a timeline 1000 showing a DRXcycle 1010 having an on-duration time interval 1012, a DRX cycle 1020having an on-duration time interval 1022, and another on-duration timeinterval 1032 beginning a next DRX cycle. For some embodiments, the DRXcycles 1010 and 1020 have the same DRX configuration parameters.

In one embodiment, the UE 126 monitors for data transmission schedulingassignments during an active time of the DRX cycle 1020 and detects adata transmission scheduling assignment during the active time at time1005. The UE 126 starts a first timer, in response to the detecting,wherein the first timer is set for a first timer value that specifies anamount of time 1026 between detecting the transmission and starting asecond timer that extends the active time by a second timer valuespecifying an amount of time 1028. The first timer value is determinedbased on one or both of a selected first TTI length from multiple TTIlengths for which the UE 126 can be enabled and/or a selected shorterfirst processing time over a second processing time associated with aTTI length used by the UE 126.

The UE 126, for example, receives a data transmission schedulingassignment at 1005 while using STTI to monitor an SPDCCH over the timeinterval 1022. The UE 126 then starts the first timer, which is set fora first timer value of 4 ms. At a later time (not shown) the UE 126receives another data transmission scheduling assignment while usingLTTI to monitor a PDCCH. The UE 126 then starts the first timer, whichis now set for a first timer value of 8 ms. In further embodiments, thesecond timer value also depends upon whether the UE 126 is scanningusing STTI or LTTI.

For some embodiments, the first timer value is a HARQ RTT timer valueused by the UE 126, and the second timer value is a DRX retransmissiontimer value used by the UE 126. In additional embodiments, the HARQ RTTtimer value used by the UE 126 is a different from a HARQ RTT timervalue used by a different UE, such as the UE 128. The RAN 110, forexample, accommodates different UEs using different HARQ RTT timervalues. In particular, the eNB 102 waits for varying amounts of timebefore sending data retransmissions to the UEs 126 and 128. In someembodiments, the varying amounts of time are due to the transmission tothe UE 126 being a STTI transmission and the transmission to the UE 128being an LTTI transmission, wherein the STTI time interval is shorterthan the LTTI time interval.

In one embodiment, a first TTI length, associated with an STTI, is usedfor sending the data transmission scheduling assignment that wasdetected during the active time interval 1022 at the time 1005. Based onthis, the UE 126 uses a particular first timer value associated with thefirst TTI length. Later, the UE 126 receives another data transmissionscheduling assignment using a second TTI length, associated with a LTTI.The UE 126 responsively uses another first timer value associated withthe second TTI length. For an additional embodiment, the second timervalue the UE 126 uses also depends upon whether a data transmissionscheduling assignment, which could not be decoded, was received usingthe first or the second TTI length.

For some embodiments, the UE 126 determines the first timer value andthen communicates the first timer value to the network, for example, viathe eNB 102. In other embodiments, the network determines the firsttimer value for the UE 126, and the UE 126 receives the first timervalue from the network. For a particular embodiment, the first timervalue corresponds to a particular downlink HARQ process.

In one embodiment, the UE 126 extends the active time interval 1022using an inactivity timer if the UE 126 receives either an LTTI or anSTTI grant. In a further embodiment, the value of the inactivity timerdepends on whether the US 126 receives an LTTI or an STTI grant.

FIG. 11 shows time sequence diagrams illustrating the first timer valuebeing determined based on a processing time associated with a TTI lengthused by the UE 126. As shown, the first timer is a HARQ RTT timer andthe second timer is a retransmission timer, consistent with the UE 126operating within an LTE network for some embodiments. For both timelines1110 and 1120, the UE 126 monitors a PDCCH for data transmissionscheduling assignments using LTTI with an associated length of onesubframe or 1 ms.

On the timeline 1110, the UE 126 receives a data transmission schedulingassignment at time 1116 occurring for the third LTTI of an on-durationtime interval 1112. The UE 126 receives and processes the datatransmission scheduled by the received data transmission schedulingassignment using LTTI but is unable to decode it. The HARQ RTT timerstarts with the reception of the data transmission scheduling assignmentat the time 1116 and runs for 8 ms, spanning eight subframes, beforeexpiring at time 1118 when a retransmission timer sets. Theretransmission timer runs for two subframes over a time interval 1114.During this time, the UE 126 actively monitors the PDCCH for anotherdata transmission scheduling assignment corresponding to theretransmission of the data transmission. With the UE 126 using LTTI, theHARQ RTT timer value of eight subframes provides sufficient time for theUE 126 to decode received data transmissions and to send ACKs to thenetwork, thereby canceling automatic retransmission of data that issuccessfully decoded by the UE 126.

Timeline 1120 is associated with a shorter HARQ RTT timer value due toshorter processing times where the UE 126 uses slot-length STTIcapability for processing received data transmission schedulingassignments and data transmissions as opposed to subframe-lengthLTTI-based processing. On the timeline 1120, the UE 126 receives a datatransmission scheduling assignment at time 1126 occurring for the thirdLTTI of an on-duration time interval 1122. The UE 126 receives andprocesses the corresponding data transmission using STTI capability butis unable to decode it.

The HARQ RTT timer starts with the reception of the data transmissionscheduling assignment at the time 1126 and runs for only 4 ms, 4 ms lessthan for LTTI-based processing capability, before expiring at time 1128.The retransmission timer runs for two subframes over a time interval1124 during which retransmission of the data transmission is expected.Using STTI for processing, the HARQ RTT timer value of four subframesprovides sufficient time for the UE 126 to decode received datatransmissions and to send ACKs to the network, thereby cancelingautomatic retransmissions of data transmissions that are successfullydecoded.

For several embodiments, the UE 126 is capable of using a shorter TTIthan a standard 1 ms TTI but uses the standard 1 ms TTI with a shorterprocessing time. This is based on only part of the processing time beingdependent on the TTI length. For an embodiment of PDSCH operation, theUE 126 performs the following tasks: decode the DL grant, channelestimation for PDSCH demodulation, PDSCH data turbo decoding, preparethe related Ack-Nack for transmission start the Ack-Nack transmission onPUCCH/PUSCH 3 TTIs (i.e. in N+4) after the end of the DL TTI carryingthe PDSCH. In some instances, the above tasks are almost independent ofthe TTI length. Therefore, the total processing time of legacy 1 ms TTIcan be reduced to 2 ms, as an example of the UE 126 having slot-levelSTTI capability, assuming linear scaling of the processing time withsupported shortened TTI length.

In some embodiments for which the first timer value is determined, atleast in part, from a shorter first processing time selected over alonger second processing time associated with a TTI length used by theUE 126, the shorter first processing time is based on a minimum timeduration between receiving an uplink grant during an active time of theUE 126 and a corresponding uplink transmission by the UE 126. Forexample, the UE 126 receives an UL grant from the eNB 102 on a controlchannel, such as a PDCCH, and references an associated time using aclock internal to the UE 126 or timing signals received from a networkvia the eNB 102. After processing the UL grant, the UE 126 makes anuplink transmission on a PUSCH and again references an associated time.The UE 126 takes a difference between the referenced times to get a timeinterval used in determining the first processing time.

In another embodiment, the network measures a time interval from when itsends the UL grant to the UE 126 to when it receives the UL transmissionfrom the UE 126. The network determines the first timer value from themeasured time interval and communicates the first timer value to the UE126.

For other embodiments, the shorter first processing time is based on aminimum time duration between the UE 126 receiving downlink data andcorresponding downlink HARQ feedback transmitted by the UE 126. Forexample, the UE 126 receives a DL transmission from the eNB 102 on aPDSCH and references an associated time using a clock internal to the UE126 or timing signals received from a network via the eNB 102. Afterprocessing the DL transmission to decode its contents, the UE 126transmits a corresponding ACK on a PUCCH or a PUSCH and again referencesan associated time. The UE 126 takes a difference between the referencedtimes to get a time interval used in determining the first processingtime.

In another embodiment, the network measures a time interval from when itsends the DL transmission to the UE 126 to when it receives the ACK fromthe UE 126. The network determines the first timer value from themeasured time interval and communicates the first timer value to the UE126.

For a number of embodiments, the PUSCH transmission time is based on thefirst processing time. Therefore, the first timer value is determinedbased on the first processing time the UE 126 is capable of. Forexample, the HARQ RTT timer value is determined by the capability of theUE to support faster receptions and transmissions rather than by ameasured time difference.

FIG. 12 shows a block diagram illustrating a method for determining afirst timer value, for example, a HARQ RTT timer value, in accordancewith some embodiments for which the first timer value is adjustablebased on one or more adjustment factors. For instance, the UE 126monitoring for data transmission scheduling assignments based on an STTIincludes the UE 126 monitoring for the data transmission schedulingassignments under the control of a DRX configuration associated with theSTTI. The DRX configuration is associated with a set of DRX parametershaving a first timer value and a second timer value, wherein the firsttimer value specifies an amount of time between detecting atransmission, while performing the monitoring, and starting a timer forthe second timer value, wherein the first timer value is adjustablebased on one or more adjustment factors.

In particular, FIG. 12 shows either a UE 1226 or an eNB 1202, dependingupon the embodiment, determining or adjusting a HARQ RTT timer value1250 based on one or more adjustment factors from a set of adjustmentfactors. The set of adjustment factors shown includes a transport blocksize (TBS) restriction 1232, a TBS 1234, TBS parameters 1236, a timingadvance (TA) restriction 1238, shortened processing time capability1240, STTI capability 1242, and a TTI length 1244. For an embodiment,the UE 1226 receives, from a network, at least one timer valueadjustment factor, which the UE 1226 uses in determining the first timervalue. Also, the UE 1226 may be configured via higher layers to operatein a low-latency transmission mode using 1 ms TTI.

The time it takes the UE 1226 to process a received DL transmission candepend upon the UE 1226 having STTI capability 1242, or with morespecificity, upon which TTI length 1244 the UE 1226 is using inparticular. The UE 1226 having a shortened processing time capability1240, as described above with respect to FIG. 11, can also provideinformation on how quickly the UE 1226 can process received DLtransmissions. By extension, because HARQ RTT timer values allow forsignal processing, these timer value adjustment factors play a part indetermining the best value for which to set a HARQ RTT timer.

Additional timer value adjustment factors include those related to TBS.A transport block is data given by an upper layer of a network to itsphysical layer for transmission. The TBS 1234 is the amount of datatransmitted with each TTI. In some instances, there is a TBS restriction1232 in which the actual data payload for a TTI is less than a fullamount of data the TTI can carry. The data payload of a TTI might berestricted, for example, if STTI signal processing is being used todecode LTTI transmissions. In some instances the UE 1226 or the eNB 1202uses TBS parameters 1236 in addition to or in place of the TBS 1234 indetermining the HARQ RTT timer value 1250. TBS parameters 1236 caninclude data used in calculating a TBS 1234, such as a number ofphysical resource blocks and/or a modulation and coding scheme. In someinstances, the TBS parameters 1236 are used to determine the TBSrestriction 1232.

The TA is a negative time offset the UE 1226 applies to a ULtransmission the UE 1226 sends to the eNB 1202 after receiving a DLtransmission from the eNB 1202. UEs apply TAs to synchronize DL and ULsubframes at the eNB 1202. The TA takes into account the travel time ofa transmission between the UE 1226 and the eNB 1202, which is directlyproportional to the distance between the UE 1226 and the eNB 1202. TheeNB 1202, for example, makes synchronized transmissions to a group ofUEs. Each UE receives its transmission at a different time because eachUE has a different distance from the eNB 1202. Each UE then advances itsresponsive UL transmission to the eNB 1202 by a TA of twice adistance-dependent propagation time for that UE. In so doing, theresponsive UL transmissions from the group of UEs are synchronized intheir arrival at the eNB 1202.

TAs can affect processing time for received DL transmission because someof the time otherwise available for processing might be needed inapplying the TA. Generally, due to a larger TA, a UE which is furtheraway from an eNB has less time to process a DL transmission than a UEwhich is closer to the eNB and receives the transmission earlier. Indifferent embodiments, different eNBs impose different TA restrictions1238. TAs, for example, can be restricted to be less than a maximumvalue and/or be limited to a finite number of discrete values.

For some embodiments, at least one received timer value adjustmentfactor includes one or more of: a set of TBS parameters 1236; a TBS1234; a TBS restriction 1232; or a TA restriction 1238. In oneembodiment, the UE 1226 receives the set of TBS parameters from thenetwork and determines the TBS 1234 based on the TBS parameters 1236.Based on the TBS 1234, the UE 1226 determines the TBS restriction 1238used in determining the first timer value. For another embodiment, theUE 1226 receives the TBS 1234 from the network and determines, based onthe TBS 1234, the TBS restriction 1232 used in determining the firsttimer value.

For a particular embodiment, multiple TBS restriction values are storedon the UE 1226, for example, in its memory. Based on a TBS 1234 or a setof TBS parameters 1236 the UE 1226 receives from the eNB 1202, the UE1226 selects a TBS restriction 1232 from the multiple stored values. Inone instance, the UE 1226 uses a look-up table to select the TBSrestriction 1232 from the multiple stored TBS restriction values.

The UE 1226 can also receive a control signal from the network. Based onthe received control signal, the UE 1226 selects a first transmissiontime interval from which the UE 1226 determines the first timer value.For example, the control signal can be a radio resource control (RRC)signal, MAC-CE signal, or a SPDCCH/PDCCH signal indicating the TTIlength.

Setting a proper value for a HARQ RTT timer can reduce scheduling delaydue to DRX operation and/or conserve energy. Further, there could bemultiple HARQ processes with each HARQ process having a different HARQRTT timer value. For one embodiment involving downlink spatialmultiplexing, if a transport block (TB) is received while a HARQ RTTtimer is running and if the previous transmission of the same TB wasreceived at least N subframes before the current subframe (where Ncorresponds to the HARQ RTT Timer), then the MAC entity processes the TBand restarts the HARQ RTT timer.

In another embodiment, the UE 1226 determines a minimum timing based ona scheduled TBS and TBS restriction. Based on the scheduled TB size(maximum TB size in case of more than single scheduled TB), the minimumtiming can be n+2 or n+3, for example, for a DL grant sent on subframe“n.” The minimum timing for UL grant to UL data and for DL data to DLHARQ for 1 ms TTI with shortened processing can be adjusted based on thescheduled TB size and TBS restrictions. If the UE 1226 is scheduled witha TBS larger than that of its corresponding TBS restriction(s) whileoperating in reduced-processing mode, the UE 1226 discards the grant.

For one embodiment, a maximum TA restriction changes for the UE 1226 asthe UE 1226 moves from a first cell with a first maximum TA restrictionto a second cell with a second maximum TA restriction. The differentmaximum TA restrictions affect the processing time capability of the UE1226. The UE 1226 determines a new processing time capability andadjusts its HARQ RTT timer value 1250.

For several embodiments, different HARQ processes may have differentHARQ RTT timer values. For example, different HARQ processes could havedifferent TTI lengths and/or TBS restrictions. The eNB 1202 can send theHARQ RTT timer value for the UE 1226 (or a group of UEs) via a PDCCH ina common search space. The eNB 1202 can send the HARQ RTT timer valuefor the UE 1226 via dedicated higher layer signaling such as MAC-CE orRRC.

FIG. 13 shows a block diagram of a UE 1300, which for particularembodiments represents the UE 126 or the UE 1226. In other embodiments,the UE 1300 represents a smartwatch, a phablet, a tablet, a personalmedia player, a personal or enterprise digital assistant, a laptop, apersonal computer, or any other electronic device that operates inaccordance with the teachings herein. Included in the block diagram area processor 1302, one or more input components 1304, one or morecommunication interfaces 1306, memory 1308, one or more outputcomponents 1310, and sensors 1312, which are all operativelyinterconnected by a bus 1314. A limited number of components 1302, 1304,1306, 1308, 1310, 1312, 1314 are shown in the UE 1300 for ease ofillustration. Other embodiments may include a lesser or greater numberof components in a UE. Moreover, other components needed for acommercial embodiment of a UE that incorporates the components shown areomitted from FIG. 13 for clarity with respect to the embodimentsdescribed.

In general, the processor 1302 is configured with functionality inaccordance with embodiments of the present disclosure as describedherein with respect to the previous figures. “Configured,” “adapted,”“operative,” or “capable,” as used herein, means that indicatedcomponents are implemented using one or more hardware elements, such asone or more operatively coupled processing cores, memory elements, andinterfaces, which may or may not be programmed with software and/orfirmware, as the means for the indicated components to implement theirdesired functionality. Such functionality is supported by the otherhardware shown in FIG. 13, including the device components 1304, 1306,1308, 1310, and 1312, which are all operatively interconnected with theprocessor 1302 by the bus 1314.

The processor 1302, for instance, includes arithmetic logic and controlcircuitry necessary to perform the digital processing, in whole or inpart, for the UE 1300 to utilize a shortened TTI length and/or ashortened processing time associated with a longer TTI length inaccordance with described embodiments. For one embodiment, the processor1302 represents a primary microprocessor, also referred to as a centralprocessing unit (CPU), of the UE 1300. For example, the processor 1302can represent an application processor of a smartphone. In anotherembodiment, the processor 1302 is an ancillary processor, separate fromthe CPU, wherein the ancillary processor is dedicated to providing theprocessing capability, in whole or in part, needed for the components ofthe UE 1300 to perform at least some of their intended functionality.For one embodiment, the ancillary processor is a graphical processingunit (GPU) for a touchscreen or another graphical output component.

The memory 1308 provides storage of electronic data used by theprocessor 1302 in performing its functionality. For example, theprocessor 1302 can use the memory 1308 to load programs and/or storefiles associated with the UE 1300 utilizing a shortened TTI lengthand/or a shortened processing time associated with a longer TTI length.In one embodiment, the memory 1308 represents random access memory(RAM). In other embodiments, the memory 1308 represents volatile ornon-volatile memory. For a particular embodiment, a portion of thememory 1308 is removable. For example, the processor 1302 can use RAM tocache data while it uses a micro secure digital (microSD) card to storefiles associated with looking up TBS restrictions.

The input component 1304 and the output component 1310 representuser-interface components of the UE 1300 configured to allow a person touse, program, or otherwise interact with the UE 1300. Different UEs fordifferent embodiments include different combinations of input 1304 andoutput 1310 components. A touchscreen, for example, functions both as anoutput component 1310 and an input component 1304 for some embodimentsby allowing a user to use an application that is optimized by the use ofSTTI and/or shorter processing times. Peripheral devices for otherembodiments, such as keyboards, mice, and touchpads, represent inputcomponents 1304 that enable a user to configure applications thatbenefit from the use of STTI and/or shorter processing times. A speakeris an output component 1310 that for some embodiments allows the UE 1300to acoustically prompt a user for input. Particular embodiments includean acoustic transducer, such as a microphone, as an input component 1304that converts received acoustic signals into electronic signals, whichcan be processed for voice recognition. In a further embodiment, the UE1300 includes one or more imaging devices as input components 1304, suchas cameras.

One or more communication interfaces 1306 allow for communicationbetween the UE 1300 and a RAN of a wireless communication system, suchas the communication system shown for the environment 100. The one ormore communication interfaces 1306 also allow the UE 1300 to communicatewith other electronic devices, such as web servers or file-storagedevices, configured to support the UE 1300 in performing its describedfunctionality. From these other devices, for example, the EU 1300 candownload and/or update software programs which configure the UE 1300 forusing STTI and/or a shortened processing time for received datatransmission scheduling assignments.

For one embodiment, the communication interfaces 1306 include a cellulartransceiver to enable the UE 1300 to communicate with other devicesusing one or more cellular networks. Cellular networks can use anywireless technology that, for example, enables broadband and InternetProtocol (IP) communications including, but not limited to, 3^(rd)Generation (3G) wireless technologies such as CDMA2000 and UniversalMobile Telecommunications System (UMTS) networks or 4^(th) Generation(4G) wireless networks such as LTE and WiMAX.

In another embodiment, the communication interfaces 1306 include awireless local area network (WLAN) transceiver that allows the UE 1300to access the Internet using standards such as Wi-Fi. The WLANtransceiver allows the UE 1300 to send and receive radio signals to andfrom similarly equipped electronic devices using a wireless distributionmethod, such as a spread-spectrum or orthogonal frequency-divisionmultiplexing (OFDM) method. For some embodiments, the WLAN transceiveruses an IEEE 802.11 standard to communicate with other electronicdevices in the 2.4, 3.6, 5, and 60 GHz frequency bands. In a particularembodiment, the WLAN transceiver uses Wi-Fi interoperability standardsas specified by the Wi-Fi Alliance to communicate with other Wi-Ficertified devices.

The sensors 1312 included in some embodiments, as indicated by brokenlines, allow the UE 1300 to detect events or environmental changesbeyond direct user-initiated input received through the input component1304. Sensors 1312 can include, but are not limited to, accelerometers,gyrometers, contact sensors, and thermal sensors. The gyrometer, forexample, detects an angular velocity or a rate of rotation for the UE1300 about one or more axes. Contact sensors detect a user's grip on theUE 1300. A single-axis or a multiple-axis accelerometer measuresacceleration for the UE 1300 in one or more directions, and thermalsensors detect a position of a user with respect to the UE 1300. For oneembodiment, the combination of sensors 1312 provide data to the UE 1300which allows the UE 1300 to make a determination that a user is gamingon the UE 1300. If the gaming is such that it would benefit fromlow-latency communication with a wireless network, a remote peer-to-peergame, for example, the UE 1300 initiates STTI and/or shorter processingtimes in accordance with embodiments described herein.

A power supply included in the UE 1300 (not pictured) represents a powersource that supplies electric power to the device components 1302, 1304,1306, 1308, 1310, 1312, 1314, as needed, during the course of theirnormal operation. The power is supplied to meet the individual voltageand load requirements of the UE 1300 components 1302, 1304, 1306, 1308,1310, 1312, 1314 that draw electric current. For some embodiments, thepower supply is a wired power supply that provides direct current fromalternating current using a full- or half-wave rectifier. For otherembodiments, the power supply is a battery that powers up and runs theUE 1300. For a particular embodiment, the battery is a rechargeablepower source. A rechargeable power source for a UE is configured to betemporarily connected to another power source external to the electronicdevice to restore a charge of the rechargeable power source when it isdepleted or less than fully charged. In another embodiment, the batteryis simply replaced when it no longer holds sufficient charge.

FIG. 14 shows a block diagram of an eNB 1400, which for particularembodiments represents the eNB 102 or the eNB 1202. Included in theblock diagram are a processor 1402, one or more communication interfaces1404, and memory 1406, which are all operatively interconnected by a bus1408. A limited number of components 1402, 1404, 1406, 1408 are shown inthe eNB 1400 for ease of illustration, and other embodiments may includea lesser or greater number of components in an eNB.

The processor 1402, for instance, includes arithmetic logic and controlcircuitry necessary to perform the digital processing, in whole or inpart, for the eNB 1400 to support UEs operating with a shortened TTIlength and/or a shortened processing time in accordance with describedembodiments. For some embodiments, the processor 1402 representsmultiple microprocessors which can operate in parallel to perform acommon task or operate independently to perform separate tasks. In otherinstances, the processor 1402 has multiple processing cores. For oneembodiment, the processor 1402 provides for encryption, decryption, andauthentication, including support for Kasumi and/or SNOW3G ciphers, forexample; ingress and egress packet parsing and management; packetordering; TCP segmentation offload, and hardware time stamping. Inanother embodiment, the processor 1402 provides the processingcapability, in whole or in part, needed for the communication interfaces1404 of the eNB 1400 to perform at least some of their intendedfunctionality.

The communication interfaces 1404 allow for communications, usingvarious protocols, between the eNB 1400 and UEs and also between the eNB1400 and entities within a wireless communication network of which theeNB 1400 is a part. The communication interfaces 1404 support, forexample, in an embodiment consistent with LTE, a Uu interface betweenthe eNB 102 and the UE 1300; a S1-MME IP interface between the eNB 102and the MME 112; an X2 interface between the eNB 102 and eNBs 104, 106,and 108; and an S1-U user plane interface between the eNB 102 and theSGW 114.

The memory 1406 provides storage of electronic data used by theprocessor 1402 in performing its functionality. For example, theprocessor 1402 can use the memory 1406 to load programs, store files,and/or cache data associated with the eNB 1400 providing support for UEsto operate with a shortened TTI length and/or a shortened processingtime in accordance with described embodiments. In one embodiment, thememory 1406 represents RAM. In other embodiments, the memory 1406represents volatile or non-volatile memory. For a particular embodiment,a portion of the memory 1406 is removable, replaceable, and/or scalable.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has,”“having,” “includes,” “including,” “contains,” “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element proceeded by“comprises . . . a,” “has . . . a,” “includes . . . a,” or “contains . .. a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially,” “essentially,”“approximately,” “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

It will be appreciated that some embodiments may include one or moregeneric or specialized processors (or “processing devices”) such asmicroprocessors, digital signal processors, customized processors andfield programmable gate arrays (FPGAs) and unique stored programinstructions (including both software and firmware) that control the oneor more processors to implement, in conjunction with certainnon-processor circuits, some, most, or all of the functions of themethod and/or apparatus described herein. Alternatively, some or allfunctions could be implemented by a state machine that has no storedprogram instructions, or in one or more application specific integratedcircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic. Of course, acombination of the two approaches could be used.

Moreover, an embodiment can be implemented as a computer-readablestorage medium having computer readable code stored thereon forprogramming a computer (e.g., comprising a processor) to perform amethod as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, a CD-ROM, an optical storage device, a magnetic storagedevice, a ROM (Read Only Memory), a PROM (Programmable Read OnlyMemory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory) and a Flashmemory. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

We claim:
 1. A method performed by a device, the method comprising:receiving, from a network, an indication to enable a first transmissiontime interval which is a shorter transmission time interval than asecond transmission time interval; and switching from monitoring fordata transmission scheduling assignments under the control of adiscontinuous reception configuration associated with the secondtransmission time interval to monitoring for the data transmissionscheduling assignments based on the first transmission time interval. 2.The method of claim 1, wherein the first transmission time intervalcomprises a first set of OFDM symbols, and the second transmission timeinterval comprises a second set of OFDM symbols.
 3. The method of claim1, wherein: the first transmission time interval has a shorter lengththan the second transmission time interval; or the first transmissiontime interval has a same length as the second transmission time intervalbut is associated with a shorter data transmission processing time thana data transmission processing time associated with the secondtransmission time interval.
 4. The method of claim 1, wherein the secondtransmission time interval is a transmission time interval with whichthe device is enabled upon initially connecting to the network.
 5. Themethod of claim 1, wherein monitoring for data transmission schedulingassignments comprises one or both of: attempting to decode datatransmission scheduling assignments; or continuously monitoring for datatransmission scheduling assignments.
 6. The method of claim 5, whereincontinuously monitoring for data transmission scheduling assignmentscomprises disabling a discontinuous reception functionality associatedwith the second transmission time interval.
 7. The method of claim 6further comprising: receiving, from the network, an indication todisable the first transmission time interval; enabling the discontinuousreception configuration associated with the second transmission timeinterval; and monitoring for the data transmission schedulingassignments under the control of the discontinuous receptionconfiguration associated with the second transmission time interval. 8.The method of claim 7 further comprising receiving, from the network, anindication to enable the second transmission time interval.
 9. Themethod of claim 1, wherein the first transmission time interval isassociated with a first discontinuous reception configuration, and thesecond transmission time interval is associated with a seconddiscontinuous reception configuration, wherein the first and seconddiscontinuous reception configurations comprise different discontinuousreception parameters, the method further comprising: enabling the firstdiscontinuous reception configuration using the associated discontinuousreception parameters to control monitoring for the data transmissionscheduling assignments based on the first transmission time interval.10. The method of claim 9 further comprising disabling the seconddiscontinuous reception configuration before enabling the firstdiscontinuous reception configuration.
 11. The method of claim 9,wherein the first discontinuous reception configuration provides alonger active time for monitoring for the data transmission schedulingassignments than the second discontinuous reception configuration. 12.The method of claim 11, wherein the discontinuous reception parametersfor the first discontinuous reception configuration comprises a firston-duration timer value, and the discontinuous reception parameters forthe second discontinuous reception configuration comprises a secondon-duration timer value, wherein the longer active time is due at leastin part to the first on-duration timer value being larger than thesecond on-duration timer value.
 13. The method of claim 9 furthercomprising: receiving first discontinuous reception parameters for thefirst discontinuous reception configuration and second discontinuousreception parameters for the second discontinuous receptionconfiguration, from the network, before receiving the indication toenable the first transmission time interval; and selecting the firsttransmission time interval and configuring the device using the firstdiscontinuous reception parameters, after receiving the indication toenable the first transmission time interval, to enable the firstdiscontinuous reception configuration.
 14. The method of claim 9 furthercomprising: receiving second discontinuous reception parameters for thesecond discontinuous reception configuration, from the network, beforereceiving the indication to enable the first transmission time interval;and receiving first discontinuous reception parameters for the firstdiscontinuous reception configuration, from the network, at the time ofor after receiving the indication to enable the first transmission timeinterval, wherein the first discontinuous reception parameters are usedto enable the first discontinuous reception configuration.
 15. Themethod of claim 1, wherein the first transmission time interval isassociated with a first discontinuous reception configuration, and thesecond transmission time interval is associated with a seconddiscontinuous reception configuration, wherein the first and seconddiscontinuous reception configurations comprise different discontinuousreception parameters, the method further comprising: determining a thirddiscontinuous reception configuration based on the first and seconddiscontinuous reception configurations; and enabling the thirddiscontinuous reception configuration to control monitoring for the datatransmission scheduling assignments based on one or both of the first orthe second transmission time intervals.
 16. The method of claim 15,where determining the third discontinuous reception configurationcomprises determining a union of at least one of the discontinuousreception parameters of the first and second discontinuous receptionconfigurations.
 17. The method of claim 16, wherein determining a unionof at least one of the discontinuous reception parameters of the firstand second discontinuous reception configurations comprises one or bothof: determining a union of a first active time for monitoring for thedata transmission scheduling assignments and a second active time formonitoring for the data transmission scheduling assignments, wherein thefirst active time is provided by the first discontinuous receptionconfiguration and the second active time is provided by the seconddiscontinuous reception configuration; or determining a union of a firstinactive time for monitoring for the data transmission schedulingassignments and a second inactive time for monitoring for the datatransmission scheduling assignments, wherein the first inactive time isprovided by the first discontinuous reception configuration and thesecond inactive time is provided by the second discontinuous receptionconfiguration.
 18. The method of claim 1, wherein monitoring for datatransmission scheduling assignments based on the first transmission timeinterval comprises monitoring for the data transmission schedulingassignments under the control of a discontinuous reception configurationassociated with the first transmission time interval which comprises aset of discontinuous reception parameters, the method furthercomprising: configuring the device for an active time for performing themonitoring and an inactive time for disabling the monitoring, whereinthe active and inactive times are based on a first parameter of the setof discontinuous reception parameters; and detecting only one part of atwo-part scheduling assignment while monitoring during the active time,and resultantly extending the active time by an additional time periodto continue performing the monitoring, wherein the additional timeperiod is based on a second parameter of the set of discontinuousreception parameters.
 19. The method of claim 1, wherein monitoring fordata transmission scheduling assignments based on the first transmissiontime interval comprises monitoring for the data transmission schedulingassignments under the control of a discontinuous reception configurationassociated with the first transmission time interval, which comprises aset of discontinuous reception parameters having a first timer value anda second timer value, wherein the first timer value specifies an amountof time between detecting a transmission, while performing themonitoring, and starting a timer for the second timer value, wherein thefirst timer value is adjustable based on one or more adjustment factors.20. A device comprising: a communication interface and processoroperatively coupled together to: receive, from a network, an indicationto enable a first transmission time interval which is a shortertransmission time interval than a second transmission time interval forwhich the device can be enabled; and switch from monitoring for datatransmission scheduling assignments under the control of a discontinuousreception configuration associated with the second transmission timeinterval to monitoring for the data transmission scheduling assignmentsbased on the first transmission time interval.